Than it should be bot proof, like higher level - cheaper offline shop... or if opposite way than offline shop should be available from level 20 only. I think its better if they base the fee for setting up a shop, by a small percentage based on of how much Adena a character at a certain lvl has the possibility to bring in when farming in a most "common way". That way it will always cost you a fair sum of Adena, even if your lvl is 27 or 55. It would take some time to adjust this, but that way Adena will go out of the system, not only in, which in the end causes price inflation. However, the price difference for setting up a shop between different char lvls isnt going be drastically high. It needs to be an amount that doesnt make people choose to rather sell all their items via low lvl chars for most profit.